[PATCH] D89217: [AMDGPU] Base getSubRegFromChannel on TableGen data

[Jay Foad via Phabricator via llvm-commits]

foad added inline comments.


================
Comment at: llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp:92-93
+  static auto InitializeSubRegFromChannelTableOnce = [this]() {
+    for (unsigned Width = 0; Width < array_lengthof(SubRegFromChannelTable);
+         ++Width)
+      for (unsigned Offset = 0;
----------------
If you use std::array you can iterate over them with range-based for loops, instead of using array_lengthof.


================
Comment at: llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp:45
+
+static const uint16_t SubRegFromChannelTableWidthMap[17] = {
+    0, 1, 2, 3, 4, 5, 6, 7, 8, 0, 0, 0, 0, 0, 0, 0, 9};
----------------
critson wrote:
> rampitec wrote:
> > This could use a comment.
> Added a detailed comment.
It doesn't explain what the 9 means. 9-1 is not a valid index into SubRegFromChannelTable. Also you have a double full stop at the end.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D89217/new/

https://reviews.llvm.org/D89217